A long-term longitudinal study of stability and change throughout adulthood will be continued with analysis of intensive open-ended interviews with 94 surviving members of the Berkeley Older Generation Study, a group who have previously been interviewed in young adulthood, middle age, and young-old age, and who are now old-old or oldest-old. Four broad sets of questions will be addressed: (1) the transition between young-old and old-old age; (2) difference between old-old (age 75 to 84) and oldest-old (age 85 and beyond) persons in the quantity and quality of change; (3) the precursors of stability and change across adulthood and their impact on psychological well-being in old age; and (4) individual differences in amount and direction of change in old age. Information has been collected in the areas of intellectual functioning, health, life satisfaction, social relationships, social supports, marriage, family relationships, retrospective perceptions of past events, personality characteristics, and demographic information. All of these will be drawn upon in many analyses of the three major domains of interest in this funding period: (a) intellectual functioning, (b) social relationships and social supports, and (c) marriage. The research is designed to increase our understanding of the relationships between internal change or continuity and situational, environmentally-linked events throughout adulthood and their input on psychological well-being in advanced old age. There are implications for public policy, as well: a knowledge of important precursors of successful aging is crucial in the design of preventive intervention programs to optimize aging.